The use and construction of outdoor equipment enclosures for housing electronics and telecommunications equipment, for example telephone equipment and optical fiber systems, in outdoor environments is well known. These enclosures are typically constructed to have at least one sealed weatherproof compartment in which the equipment is housed. The enclosure will be provided with an opening for access into the equipment compartment or compartments thereof, and a door for being opened and closed on the opening. The door will typically be adapted to be sealed on at least one interior compartment of the enclosure. As the use of telecommunications systems and optical fiber systems has proliferated, greater and greater numbers of outdoor equipment enclosures of this type are now found in a great many locations, to include industrial parks, commercial installations, as well as in residential areas.
Over the course of the past several years, as a result of improvements in the design and construction of electronics, telecommunications, and optical fiber equipment and systems, the power densities of this equipment and these systems have been steadily rising. As a result, therefore, natural convection on the exterior of the outdoor equipment enclosure, which has long been the norm for cooling the interior compartment(s) of the enclosure, can no longer sufficiently cool these newer generations of equipment and systems. As known to those skilled in the art, as the temperature of the equipment increases, the performance of the equipment, and the system of which the equipment is a part, will degrade. As a result, therefore, manufacturers of these outdoor equipment enclosures, as well as telecommunications systems manufacturers and providers, have been seeking ways to cool the equipment housed within these enclosures. Additionally, at least one battery is oftentimes provided for use with the equipment housed within these enclosures. In similar fashion, and as also known in the art, sustained increases in the temperature of the battery within the enclosure tends to decrease the service life of the battery, necessitating costly servicing and/or replacement of the battery.
Examples of solutions to the problem of cooling the equipment housed within an outdoor equipment enclosure of the type discussed are disclosed in several U.S. patents. Common among these patents, however, is the construction of a heat exchanger/heat exchange system directly within the enclosure, also referred to as an equipment cabinet, for the purpose of drawing and/or passing ambient air from outside the equipment enclosure through the enclosure for the purpose of cooling the equipment housed therein. These types of structures are disclosed in U.S. Pat. No. 4,949,218 to Blanchard, et al.; U.S. Pat. No. 5,570,740 to Flores, et al.; U.S. Pat. No. 5,603,376 to Hendrix; U.S. Pat. No. 5,765,743 to Sakiura et al.; and U.S. Pat. No. 5,832,988 to Mistry, et al.
Although the heat exchangers of the aforementioned patents have been designed to cool the air within an outdoor equipment enclosure, they do so with structures that are relatively complicated in construction, and which oftentimes increase the size, and necessarily the expense, of the enclosure in order to house not only the telecommunications or electronics equipment, but also the heat exchange system. Moreover, the complexity of these heat exchange systems, and the difficulties in sealing these heat exchange passages as they pass through the interior compartments of the equipment enclosure lead to potential problems in leakage of the ambient air being passed through the heat exchanger into the sealed interior compartment, or compartments, of the enclosure, thus allowing dust and other airborne debris to be deposited on the equipment, which may cause equipment shorts, and/or may cause the equipment to overheat due to the build up of this debris over time.
In an effort to provide a simpler solution to the problem of cooling outdoor equipment enclosures, door mounted heat exchangers have been developed. Examples of door mounted heat exchangers are found in U.S. Pat. No. 4,535,386 to Frey, Jr., et al; and in U.S. Pat. No. 5,467,250 to Howard, et al. In the '386 patent to Frey, Jr., et al., the outdoor equipment enclosure is constructed such that an "inner chimney" is formed which separates the enclosure into forward and rearward compartments. This allows for the circulation of air through the chimney and about the compartments. The enclosure is provided with a door which seals the access opening of the enclosure, this door being provided with several sealed air passages which will permit ambient air to flow therethrough in the hope that the door will act as a heat exchanger for cooling the air within the enclosure when the air within the sealed part of the enclosure comes into contact with the door. Although Frey, Jr., et al. disclose a simple solution to the cooling of outdoor equipment enclosures, it is not well adapted for the newer generations of telecommunications and electronics equipment housed within these enclosures because of the aforementioned problems of increased power densities. Frey, Jr., et al. disclose a strictly passive heat exchange system which provide no means for positively cooling the enclosure such that heat build up within the enclosure is prevented. Another drawback of the device of Frey, Jr., et al. is that as a passive system, if the air passages within the door of the enclosure become plugged with debris, as is likely to occur over time, the heat exchange construction of the door is mitigated.
In the patent to Howard, et al. an electrical cabinet is disclosed in which a heat exchanger is housed within the door, or doors, of an equipment cabinet, but the door itself does not function as a heat exchanger. The electrical cabinet of Howard, et al. utilizes a fan shelf/compartment constructed within and as a part of the cabinet for holding two spaced series of fans, the fans being in communication with two separate ducts, or series of vents, within the door for drawing ambient air through a first series of these vents, and for passing air from the inside of the cabinet through the second series of vents so that the ambient air will cool the air circulated Within the interior of the cabinet as it is passed through the second series of vents. Although the construction of the electrical cabinet/door mounted heat exchanger of Howard, et al. avoids some of the complexities of the constructions of the heat exchange systems in the patents discussed above, it is still a rather complicated construction which requires at least one separate fan compartment within the cabinet, plus two sets of heat exchange ducts, all of which need to be sealed within and on the cabinet in order to prevent leakage of outside air into the sealed compartments of the enclosure. Moreover, as the construction of the device of Howard, et al. is relatively complex, it will likely require increased maintenance over time, and will also cause the construction of the electrical cabinet, or cabinets with which the system is used to be more expensive.
What is needed, but seemingly unavailable in the art, is a simple door mounted heat exchanger for use with outdoor equipment enclosures which will allow the inner equipment and/or battery compartments of the enclosure to be cooled without an intrusive heat exchange system constructed as a part of and housed within the enclosure, and which can accomplish this need in simple fashion without the unduly complicated constructions of the known devices. What is also needed is a means of cooling not only the equipment within the enclosure, but a means for cooling the batteries housed within these enclosures as well. Moreover, there is a need for a heat exchange system for use with outdoor equipment enclosures which can easily be fit or retrofit to existing constructions of equipment enclosures in an expedient, cost-effective fashion in order to allow for the effective cooling of the electronics/telecommunications equipment housed within these enclosures.